1. Field of the Invention
The present invention relates to a process for producing norbornane dimethylene amines (bicyclo[2.2.1]heptane bis(methylamine)'s) by hydrogenating norbornane dicarbonitriles (bicyclo[2.2.1]heptane dicarbonitriles).
2. Description of the Related Art
Heretofore, it has been known that diamines are produced by hydrogenating dinitriles in the presence of a metal catalyst such as cobalt, nickel or platinum, but the present situation is that the preferable reaction conditions, reaction yields etc. are greatly varied depending on the type of individual dinitriles and thus the process fails to satisfy industrial production levels.
As a method of producing norbornane dimethylene amines by hydrogenating norbornane dicarbonitriles, a method of using a Raney cobalt catalyst (Japanese Patent No. 2713612) or a method of using a Raney nickel catalyst (Japanese Patent No. 2713615), in the presence of an organic solvent and ammonia, are known.
In connection with the foregoing, it is known that when a cobalt-carried catalyst having cobalt carried on a carrier such as silica, alumina or silica-alumina is used, the catalyst can maintain its activity for a prolonged period of time and thus can be repeatedly used several times (Japanese Patent No. 2713623).
Although the catalyst is re-usable in the method described in Japanese Patent No. 2713623 supra, it cannot be said in consideration of industrial production that the number of times the catalyst can be repeatedly used is sufficient, and thus a considerable amount of the catalyst is still required in production of norbornane dimethylene amines by hydrogenation of norbornane dicarbonitriles. Further, because of requiring not only a large amount of the catalyst but also high costs in the disposal of the used catalyst or in the process of regeneration of the catalyst, this method needs further improvement in order to achieve economical and industrial production of norbornane dimethylene amines.
Meanwhile, Japanese patent publication No. (JP-B) 1-52381 has reported a method of hydrogenating aliphatic nitriles, alkylene oxynitriles or alkylene aminonitriles into primary amines wherein the hydrogenation is carried out using a cobalt or ruthenium catalyst in an ammonia-containing ether solvent and in the presence of water in an amount ranging about 5 to 15% by volume of the ether solvent, whereby the life of the catalyst is prolonged about twice as long as that of the catalyst in the absence of water.
However, the type of dinitrile used in the method described in the above publication is different from the type of dinitrile used as the starting material in the present invention, and further even if the life of the catalyst is improved, its life is still not satisfactory. In addition, it is shown therein that the ether solvent is required in an amount of about 75 to 95% by weight relative to the starting nitrile while water is required in an amount of about 20 to 300% by weight relative to the starting nitrile in order to achieve a sufficient yield of the primary amines to be produced.
That is, in the method described in JP-B 1-52381 supra, the solvent and water are used in large amounts relative to the starting nitrile so that the productivity of the desired primary amines is lowered and enormous energy is necessary for separation or recovery of the solvent and water after the reaction. Hence, this prior art cannot be deemed to be a method capable of producing the product efficiently, economically and inexpensively on the industrial scale.
Further, Japanese patent publication No. (JP-B) 54-40524 discloses production of tetramethylene diamine by hydrogenating succinonitrile wherein the reaction is carried out in the presence of a Raney cobalt catalyst containing manganese. It is described in the Examples therein that the catalyst was able to be used repeatedly up to 50 times in the hydrogenation reaction.
However, the type of dinitrile described in the publication mentioned above is different from the starting material used in the present invention, and even if the catalyst can be used repeatedly, this result could be achieved under those conditions where the catalyst, a solvent and ammonia are used in very large amounts, that is, the amount of metal cobalt as the catalyst is 39% by weight, the amount of dioxane used as the solvent is 600% by weight, and the amount of liquid ammonia used is 600% by weight each ralative to the starting material, succinonitrile.
That is, in view of the amount of the catalyst used, the number of times the catalyst can be repeatedly used can be evaluated to be insufficient in the method described in JP-B 54-40524 supra. Further, this method is a method in which not only the catalyst but also the solvent and liquid ammonia are used in large amounts relative to the starting succinonitrile, so that the productivity of the desired tetramethylene diamine is lowered and enormous energy is necessary for separation or recovery of the used solvent and ammonia after the reaction. Hence, this prior art cannot be deemed to be a method capable of producing the product efficiently, economically and inexpensively on the industrial scale.
To produce norbornane dimethylene amines economically and inexpensively by hydrogenation of norbornane dicarbonitriles in the industrial scale, it is essential for the life of the catalyst used for hydrogenation to be long. In the prior art methods, however, the life of the catalyst cannot be sufficiently long, as described above, and even in the method of using a large amount of solvent and water, the life of the catalyst is still unsatisfactory.
The object of the present invention is to provide a process for producing the desired norbornane dimethylene amines efficiently, economically and inexpensively with the sufficiently longer life of the catalyst used for the reaction than in the prior art described above.